Convert page pdf to image

I'm in the fight to perfectly convert a PDF to an image.
But the stacktrace below breaks my application!

—
Out 02, 2013 3:22:35 PM org.apache.pdfbox.pdmodel.graphics.xobject.PDPixelMap getRGBImage
SEVERE: Something went wrong ... the pixelmap doesn't contain any data.
Out 02, 2013 3:22:35 PM org.apache.pdfbox.util.operator.pagedrawer.Invoke process
WARNING: getRGBImage returned NULL
Out 02, 2013 3:22:35 PM org.apache.pdfbox.util.PDFStreamEngine processOperator
INFO: unsupported/disabled operation: i

—
I really need to fix this problem in order to succeed in converting
You know why this error occurs?
You know how I can fix this error?
is some dependence of my environment that i forgot? or a failure of PDFBox framewor ?

Follow my code below:
—

public static List<BufferedImage> getPdfPagesAsImages(String pdfPath, int i)
throws FileNotFoundException, IOException {
List<BufferedImage> bImages = new ArrayList<BufferedImage>();

File f = new File(pdfPath);
if (f.exists()) {
int resolution = 185;
PDDocument pdfDocument = null;

pdfDocument = PDDocument.loadNonSeq(f, null);

if (pdfDocument != null) {
@SuppressWarnings("unchecked")
List<PDPage> pages = (List<PDPage>) pdfDocument
.getDocumentCatalog().getAllPages();
int j = 1;
for (PDPage p : pages) {
System.out.println(j);
BufferedImage convertedImage = p.convertToImage(
BufferedImage.TYPE_INT_BGR , resolution);
saveImageToRepository(i, j, convertedImage);
j++;
if (isNegativeImage(convertedImage))

{ bImages.add(invertNegativeImage(convertedImage)); }

else

{ bImages.add(convertedImage); }

}
System.out.println(pdfPath +" sucess");
}
pdfDocument.close();
}else

{ System.out.println(pdfPath +" nao existe"); }

return bImages;
}

private static void saveImageToRepository(int i, int j,
BufferedImage convertedImage) throws IOException

{ File outputfile = new File("C:/Desenvolvimento/bkp/convertido/" + i + j+ ".png"); ImageIO.write(convertedImage, "png", outputfile); }

—
I create a list of images
these images are saved to be loaded in the browser later on a JSF component.

Thank you!